George T. Hida et al. U.S. Pat. No. 5,030,600 discloses a composite material containing at least 70 weight percent of single-phase beta sialon and at least 20 weight percent of alpha-alumina. Although the composite material of this patent has excellent mechanical and thermal properties, the oxidation resistance of such material, after exposure to temperatures in excess of 1,200 degrees Centigrade, is often less than ideal.
It is an object of this invention to provide a precursor composition which may be used to prepare a beta-sialon material which has substantially better oxidation resistance properties than the oxidation resistance properties of the beta-sialon compositions of U.S. Pat. No. 5,030,600.
It is another object of this invention to provide a novel precursor material comprised of free silicon, alumina, and beta-sialon, wherein the precursor material, upon being heated, will form a sialon bond phase and will bond oxide or nonoxide material (such as, e.g., cordierite, zirconia, silicon carbide, siicon nitride, titanium nitride, and boron nitride).
It is yet another object of this invention to provide a novel, bonded material comprised of oxide or nonoxide material and beta-sialon.
It is another object of this invention to provide a process for preparing said precursor material.
It is yet another object of this invention to provide a process for heat-treating said precursor material to form the beta-sialon composition.
It is another object of this invention to provide a beta-sialon composition whose mechanical properties are superior to those of the composite material of U.S. Pat. No. 5,030,600.
It is another object of this invention to provide a novel process for preparing the beta-sialon material of this invention.
It is an additional object of this invention to provide a beta-sialon composition which can be sintered without pressure into a high-density body which possesses good mechanical and thermal properties.
It is another object of this invention to provide a beta-sialon composition which can be sintered without the use of sintering aids.
It is another object of this invention to provide a novel sintering aid comprised or consisting of beta-sialon which may be used to facilitate the sintering of many nonoxide materials.
It is another object of this invention to provide a novel sintering aid which, under the conditions commonly used in sintering, produces an intergranular sialon crystalline phase.
It is another object of this invention to provide a novel sintered ceramic material comprised of crystalline beta-sialon which has superior mechanical and/or thermal properties.
It is another object of this invention to provide a pellet which can be used to produce the precursor material of this invention.
It is another object of this invention to provide a beta-sialon composition which is reinforced and has improved mechanical properties.
It is another object of this invention to provide a primarily synthesized beta-sialon composition.
It is yet another object of this invention to provide a controlled, self-sustaining, highly-exothermic process for the production of a beta-sialon material at a cost substantially less than that presently incurred for the preparation of the prior art "Sialon" materials.